These rankings do not depict mallard abundance; they indicate the relative progression of the fall migration. Estimated peak numbers of mallards may be lower or higher than average numbers during previous years due to annual variations in local wetland and environmental conditions. As a result, a dark color does not necessarily mean that lots of mallards are present in that region

These maps depict real time estimates of migration without the benefit of waiting until the completion of migration before providing assessments. Some variation in results may also occur depending on the number of experts reporting for a given week.